Re: Clean Object Class Design -- Circle/Ellipse

>Is it still true that "any model of inheritance in which type
>Integer is not considered to be a subtype of type Real
>can hardly be said to be a good model of reality" ?

Yes. It is still true. All of the operators on Real to yield Real apply equally when one substitutes an Integer for the Real operand, and all of the operators on Real to yield Integer apply equally when one substitutes an Integer for the Real operand.

Integers may have additional operators and properties that do not apply to all Reals, which makes Integer a proper subtype of Real.

Quite frankly, I do not think it is Date who misunderstands "type".

>To put bluntly, " Type Inheritance: Is a Circle an Ellipse?"
>documents lack of understanding of types (and OO),
>and the usefulness of Date's inheritance model approaches zero.

Your statement is not only blunt: It is also an extraordinary statement requiring extraordinary proof, which you have failed to provide, and to put it bluntly, it is also incorrect. Received on Sat Aug 04 2001 - 14:22:40 CDT